Dart Nextcloud Talk API not compatible with newest Talk API

[dajevtic]

client.dart for talk API specifies the following baseUrl for talk management:

final _baseUrl = '$baseUrl/ocs/v2.php/apps/spreed/api/v1';

However, though this may be true for _guestManagement, _messageManagement it does not apply to
_conversationManagement anymore.
The correct baseUrl would be:

final _baseUrl4 = '$baseUrl/ocs/v2.php/apps/spreed/api/v4';
_conversationManagement = ConversationManagement(network, _baseUrl4);

Furthermore 2 members marked as required in Conversation have been removed, therefore they should be removed in order for the talk API to be intact again for new Nextcloud Talk version.
The 2 members affected, that should be removed, are:

  /// The count of active users
  final int userCount;

  /// The number of active guests
  final int guestCount;

I tried this on my local machine and the Talk API basic functions work again. Hope it helps in keeping future compatibility.

[provokateurin]

Hey! If you submit a fix I'll merge it. I don't plan to work on this implementation anymore. See #55 (comment) on how this library will live on.

[provokateurin]

Implementation of the latest Talk API is planned here: nextcloud/neon#1